Effects of Glycine on Proliferation and Apoptosis of Mammary Epithelial Cells of Dairy Cows

The objective of this experiment was to study the effects of glycine on proliferation and apoptosis of in vitro cultured mammary epithelial cells of dairy cows. The 2nd generation of mammary epithelial cells of Chinese Holstein dairy cows were used. Cells were divided into 6 groups,and were cultured in DMEM /F12 supplemented with 0,1,2,5,10 and 20 mmol /L glycine,respectively. There were 6 replicates in each group for the analysis of cell proliferation after cultured for 24,48 and 72 hours( the test was repeated for 3 times),and there were 4 replicates in each group for the analysis of cell apoptosis rate and the proportion of cells in different cell cycles. The results showed as follows: compared with 0 mmol /L group,1) the cell proliferation ability was improved in 1 mmol /L group,but the difference was not significant( P0.05); the supplementation of 10 to 20 mmol /L glycine in culture medium significantly decreased the cell proliferation ability( P0.05).2) The supplementation of 2 to 20 mmol /L glycine in culture medium significantly increased the cell apoptosis rate( P0.05),and the rate in 20 mmol /L group was significantly higher than that in the other groups( P0.05). 3) The proportion of cells in S phase in 20 mmol /L group was significantly increased( P0.05); the supplementation of 5 to 20 mmol /L glycine in culture medium tended to increase G2 phase /M phase,but the difference was not significant( P 0. 05). In conclusion,glycine can regulate proliferation and apoptosis of mammary epithelial cells of dairy cows,has a lowlevel( 1 mmol /L) stimulative and high level( 10 to20 mmol /L) inhibitive effect on cell proliferation and a stimulative effect on cell apoptosis,and can promote the conversion of mammary epithelial cells to S phase and cell division.